Strange RED LIGHT from the side of phone

hello

has anyone ever noticed a strange red light on the side of their phone. This has not happened to me personally, but it has happened to both of my parents and they use iPhone 12 Pro and iPhone Xs. Make no mistake, this light that is shown to them does not come from the middle where the notch is (where the infrared light that scans the face is) but literally from the side of the phone. It appears to them every day 2-3 times at different times.... I wonder if anyone can explain this phenomenon?? or this has happened to someone